The present disclosure relates to the subject matter disclosed in German Application No. 100 12 167.5 of Mar. 13, 2000, the entire specification of which is incorporated herein by reference.
The invention relates to a screen element for motor vehicles, in particular, a wind blocker or a sun protection, comprising a frame and a piece of flat material held by the frame and extending over an area enclosed by the frame.
Screen elements of this type are known from the state of the art. In these cases, the piece of flat material is fixed on the frame by means of force locking, for example, by the pressing in of an elastic ring.
Such a fixing of the piece of flat material causes problems since the production of the force-locking connection is expensive and, in addition, the force-locking connection does not always display the desired fatigue strength.
The object underlying the invention is therefore to improve a screen element of the generic type in such a manner that this is simple to produce and has as permanent a connection as possible between the piece of flat material and the frame.
This object is accomplished in accordance with the invention, in a screen element of the type described at the outset, in that the piece of flat material is fixed permanently on the frame in that at least one frame part element consisting of a plastic material is connected to an additional part by way of a connecting area of the plastic material which is heated up by means of a sonotrode, softened and hardened.
The advantage of the inventive solution is to be seen in the fact that the melting of the plastic material, preferably, a thermoplastic material by means of a sonotrode offers a simple possibility of fixing the piece of flat material on the frame, on the one hand, inexpensively and, on the other hand, permanently.
A particularly preferred embodiment of the inventive solution provides for the frame part element to be connected to the edge area of the piece of flat material as additional part, i.e. that a direct connection between the frame part element and the edge of the piece of flat material can be produced by way of the softening and hardening of the connecting area.
This solution is particularly advantageous since it allows a secure fixing of the piece of flat material on the frame without any complicated connection techniques having to be used.
Such a fixing of the edge area of the flat material on the frame allows, in particular, automation of the production and thus an extremely inexpensive production.
Such a connection between the edge area of the piece of flat material and the frame part element can be produced in the most varied of ways.
One advantageous embodiment, for example, provides for the edge area of the piece of flat material to be embedded in the connecting area softened by the sonotrode and subsequently hardened. This means that no change in the material of the piece of flat material itself takes place as a result of the action of the sonotrode but merely an embedding thereof in the softened and subsequently hardened connecting area and thus a type of form-locking connection between the edge area of the piece of flat material and the frame part element.
A particularly favorable connection can be produced when the flat material is a woven or knitted or braided fabric so that the softened or melted plastic material saturates the edge area of the woven or knitted or braided fabric and thus embeds the fibers thereof in the connecting area essentially undamaged so that an extremely permanent, form-locking connection between the edge area of the flat material and the frame part element can be produced.
Alternatively thereto, an additional advantageous embodiment of the invention provides for the piece of flat material to be produced from a plastic material which can likewise be heated up by ultrasound, softened and subsequently hardened and has formed a connection, for example, a type of welding connection with the plastic material of the frame part element due to the softened plastic materials flowing into one another.
This solution expressly provides for the alteration of the geometrical shape of the material of the piece of flat material insofar as this is likewise melted and thus forms an intimate connection with the plastic material of the area of the frame part.
In the case of fibers, this presupposes that the fibers lose their fiber structure and, insofar as they extend through the connecting areas, have formed an intimate connection with the plastic material of the frame part element in the connecting areas due to softening.
In principle, the inventive solution also comprises all the solutions, with which an inventive connection is produced between the edge area of the piece of flat material and the frame along a connecting line, wherein the connecting area can therefore extend along the connecting line.
A particularly preferred solution does, however, provide for the edge area of the piece of flat material to be fixed on the frame part element in connecting areas arranged so as to follow one another at a distance along a connecting line. Such a solution has the great advantage that, as a result of the connecting areas being arranged in spaced relationship, even in the case of any damage to the edge area of the piece of flat material, either due to damage to the fibers or to too great a softening of the material, this cannot continue along the entire connecting line but is always interrupted.
In addition, the effect of the ultrasound is even better and more greatly localized due to the connecting areas being arranged at a distance from one another and so the connection between the frame part element and the respectively other part can also be produced in a more defined manner, in particular, with a defined softening of the plastic material.
In this respect, it is particularly favorable when the connecting areas are arranged at a distance from one another which corresponds in its order of magnitude to the extension of the connecting areas in the direction of the connecting line.
In principle, it would be conceivable to define the connecting areas in that these result due to the ultrasonic effect, for example, with local pressure due to the sonotrode, in addition.
However, in order to avoid any undefined formation of the connecting areas in this respect, as well, it is preferably provided for the connecting areas to be predetermined by plastic material agglomerations. Such plastic material agglomerations not only have the advantage that a specific local effect of the ultrasound can be achieved during the formation of the connection but also the advantage that enough material is available in the case of the plastic melt then forming to create a secure connection between the frame part element and the corresponding part, i.e. the edge area of the flat material or the other part to be connected.
Particularly when the flat material is a woven or knitted or braided fabric it is advantageous when sufficient plastic material is available for the plastic material melt which can then reliably saturate the edge area of the woven or knitted or braided fabric and thus embed the fibers.
The advantage of a sufficiently large quantity of plastic material being available is, however, also given in the case where the material of the edge area of the piece of flat material melts since, as a result, a good connection of the two melting materials is possible.
The presence of such a plastic material agglomeration may be achieved in any desired manner. For example, it would be conceivable to apply, in addition, particles of plastic material or powdered plastic material to the connecting areas provided prior to any action of the sonotrode.
However, the plastic material agglomeration later desired can be achieved particularly advantageously when the frame part element is provided with the plastic material agglomerations forming the connecting areas.
A particularly advantageous embodiment of the inventive solution provides for the edge area of the flat material to be fixed permanently on the frame part element only in the connecting areas following one another along the connecting line, i.e. that the permanent fixing extends only to the connection of the edge area of the flat material with the corresponding frame part element and no additional, permanent fixing of the flat material is provided. Such a solution has proven to be particularly inexpensive.
In conjunction with the embodiment described thus far, it has primarily been assumed that the other part, which is intended to be connectable to the frame part element for the heating up and softening of the plastic, is the edge area of the flat material.
Another, advantageous solution provides, however, for the other part to be an additional frame part element of the frame and for the frame part elements to be connected permanently to one another by way of a connecting area formed due to heating up and softening as well as hardening of the plastic material by means of the sonotrode.
Although this solution does not automatically provide for an inventive connection due to softening of the plastic material between a frame part element and the edge area of the flat material but does not exclude such a connection, this solution is advantageous since the possibility can be created in a simple manner, by connecting the two frame part elements, of also permanently fixing the edge area of the piece of flat material advantageously and, in particular, as a result of inexpensive production.
A particularly favorable form of realization provides for the end area of the piece of flat material to be connected to the wind blocker frame by form-locking elements, wherein these form-locking elements lead to a secure connection between the frame and the edge area of the piece of flat material when the two frame part elements connected to one another permanently via a connecting area prevent the form-locking elements holding the piece of flat material on the wind blocker frame from disengaging.
Alternatively thereto, it is, however, also conceivable to provide such form-locking elements in addition to all the solutions, with which the edge area of the piece of flat material is connected directly to at least one of the frame part elements due to softening and hardening of the plastic material.
In the case of such a form-locking connection between the frame and the edge area of the piece of flat material, one form-locking element is to be associated with the edge area of the piece of flat material.
In order to be able to connect this form-locking element reliably to the flat material it is preferably provided for the form-locking element associated with the flat material to be integrated into an edge reinforcement of the flat material so that a secure and stable connection exists between the flat material and the form-locking element.
In the simplest case, it is provided for the flat material to have form-locking elements designed as openings in its edge area.
Openings of this type may be produced particularly simply since no additional element has to be fixed on the edge area of the piece of flat material.
Furthermore, openings of this type are advantageous, in particular, in the case of woven or knitted fabrics since these can be designed such that they do not increase in size when stressed.
In this respect, it is particularly advantageous when the woven or knitted fabric is designed so as not to tear further or the openings are stabilized, in addition, against any further tearing.
When providing form-locking elements of the piece of flat material designed as openings it is favorable when the openings are penetrated by form-locking elements held on at least one of the frame part elements.
Form-locking elements of this type may, for example, be projections or cams or pins which are arranged on one of the frame part elements.
It is, however, also conceivable to form such form-locking elements by way of material agglomerations which result due to the effect of the sonotrode, i.e. due to the heating up and melting of plastic material.
For example, form-locking elements of this type may be pins or elevations provided on one frame part element which are deformed due to the ultrasonic effect and the resulting softening, i.e., are, for example, of a mushroom-like design so that they can permanently hold the respective opening they penetrate and thus the opening cannot disengage from the form-locking element.
In conjunction with the preceding explanations concerning the individual embodiments of the inventive solution, it has not been discussed in detail how the wind blocker frame itself is designed.
In the simplest case, the wind blocker frame can have a single frame part.
It is, however, also conceivable for the wind blocker frame to be constructed in several parts and for the frame part element required for the production of the connecting area to be only one part of the frame.
Another advantageous solution provides for the wind blocker frame to have frame parts abutting on one another along a dividing surface from opposite sides thereof and for the edge area of the piece of flat material to be held between them.
Such a solution allows a particularly secure and reliable fixing of the edge area of the piece of flat material on the frame.
One conceivable solution would be for the flat material to be held by form-locking elements extending between the two frame parts.
Form-locking elements of this type could, for example, be burls or cams integrally formed on one of the frame parts.
A particularly favorable solution provides for the form-locking elements to be formed by connecting areas connecting the frame parts and resulting due to softening and hardening of the plastic material, i.e. that the form-locking elements are, on the one hand, connecting areas which are created by the action of the sonotrode and connect the two frame parts to one another but, on the other hand, also represent at the same time form-locking elements which fix the edge area of the piece of flat material as such.
In this case, it is, for example, not absolutely necessary for a direct connection to exist via softened or melted plastic material between the edge area of the piece of flat material and one of the frame parts. It is sufficient for the frame parts themselves to be securely connected to one another and thus prevent the edge area of the piece of flat material from disengaging with its form-locking element from the form-locking element which connects the two frame parts to one another.
For example, the openings in the solution described above can already be preworked, i.e. the openings are already present in the edge area of the piece of flat material when this is placed on the corresponding frame part.
Alternatively thereto, it is, however, also conceivable for the openings to result in the edge area of the piece of flat material during the melting of the plastic material for the formation of the connecting areas due to heating up of the material forming the piece of flat material, i.e. that the openings do not result until the connecting areas are created between the two frame parts.
A further, advantageous solution provides for the connecting areas to be arranged directly between the frame parts and free from contact relative to the edge area of the piece of flat material for the permanent connection of the frame parts, i.e. that the connecting areas serve merely to fix the frame parts relative to one another but, on the other hand, the fixing, for example, the form-locking fixing of the edge area of the piece of flat material is brought about independently of the connecting areas formed due to the action of the sonotrode.
In conjunction with the explanations concerning the preceding embodiments no details have been given as to how the piece of flat material is intended to be held on the frame.
For example, it would be conceivable to produce the piece of flat material from a material which is, in itself, inherently inflexible so that a connection between the piece of flat material and the frame creates an inventive screen element.
In all the cases where the piece of flat material is, however, produced from a material which has a bending slackness it is preferably provided for the piece of flat material and the frame to be fixed relative to one another with initial tension, i.e. that in the case of the screen element itself the piece of flat material is always held in a clamped manner in the frame in order to achieve an advantageous optical effect of the piece of flat material.
Another solution provides alternatively to this for the piece of flat material to be clamped by means of a clamping member held on the frame, i.e. that an additional clamping member is provided on the frame which sees to it that the piece of flat material is held in the frame in a clamped manner.
One advantageous form of realization for this provides for the clamping member to be arranged on an attachment part fixed on the frame, i.e. that a part can be placed on the frame which bears the clamping member, namely positioned relative to the frame such that this provides for a clamping of the piece of flat material.
Another alternative solution provides for the clamping member to be arranged on one of two frame parts which are connected to one another so that the clamping member begins to act on the piece of flat material as a result of connection of the frame parts and thus the piece of flat material is acted upon such that this is held in the frame in a clamped manner.
A particularly favorable clamping of the piece of flat material may be achieved when the clamping member is of an elastic design.
In addition, the invention relates to a process for the production of a screen element for motor vehicles, in particular, a wind blocker or sun protection, comprising a frame and a piece of flat material held by the frame and extending over an area enclosed by the frame, wherein, in accordance with the invention, the piece of flat material is fixed permanently on the frame in that at least one frame part element consisting of a plastic material is connected to an additional part by way of a connecting area of the plastic material which is heated up by means of a sonotrode, softened and hardened.
The advantages of this inventive process are the same as those disclosed in conjunction with the inventive screen element, in particular, the advantages are to be seen in the simple producibility of such a screen element.
In this respect, it is particularly favorable when the at least one frame part element is connected to an edge area of the piece of flat material as additional part. It is possible to achieve a secure fixing of the piece of flat material on the frame in a particularly simple manner due to the direct connection of this type of the edge area of the piece of flat material to the frame part element.
Such a possibility provides for the piece of flat material to be embedded in the area softened by the sonotrode and subsequently hardened so that it is not necessary to melt the piece of flat material itself but rather a type of xe2x80x9cform-locking fixingxe2x80x9d can be brought about by this embedding.
Another possibility provides for the piece of flat material to be produced from a plastic material which is likewise heated up by ultrasound as well as softened and as a result a type of xe2x80x9cweld connectionxe2x80x9d is generated with the plastic material of the frame part element due to the softened plastic materials flowing into one another.
With this variation of the inventive solution, it is thus possible to produce a true weld-like connection between the piece of flat material and the plastic material of the frame part element.
With respect to the type of production of the connection it would be conceivable to create a continuous constant connection along a connecting line. It has, however, proven to be particularly favorable and simple to cope with from the point of view of the technical process when the edge area of the piece of flat material is fixed on the frame part element in connecting areas arranged so as to follow one another at a distance along a connecting line.
Alternatively to providing the solution, with which the piece of flat material is fixed directly on the frame part element, it is likewise conceivable for the other part to be an additional frame part element of the frame and for the frame part elements to be connected to one another by a connecting area formed by way of the heating up, softening and hardening of the plastic material by means of the sonotrode.
As a result, there is no direct connection between the at least one frame part element and the piece of flat material but this solution likewise creates the possibility of fixing the piece of flat material securely and permanently due to the permanent connection of the frame part elements.
A further embodiment of an advantageous inventive solution provides for the frame to be formed from frame parts which abut on one another along a dividing surface from opposite sides thereof and between which the edge area of the piece of flat material is arranged.
This solution has the great advantage that the piece of flat material can be held securely between the two frame parts, wherein, on the one hand, it is possible merely to connect the frame parts to one another by way of a connecting area obtained due to melting of the plastic material but, on the other hand, it is also possible to connect the piece of flat material to at least one of the frame parts likewise via a connecting area consisting of melted plastic material.
With respect to the fixing of the piece of flat material on the frame, no further details have so far been given. One advantageous solution, for example, provides for the piece of flat material and the frame to be fixed relative to one another with initial tension. Such a fixing of the two relative to one another with initial tension can be realized in the most varied of ways.
For example, it is conceivable to tension the piece of flat material prior to fixing it on the frame and in this pretensioned position to fix it on the frame.
Another advantageous solution provides for the frame to be deformed in a manner acted upon by a force and then connected to the piece of flat material so that the frame, after release of the force acting upon it, has the tendency to move back into the original shape and thereby clamp the piece of flat material on account of its spring elastic properties.
Another advantageous solution provides for the piece of flat material to be clamped on the frame by providing a clamping member.
Such a solution provides first of all for a fixing of the flat material with little or slight tension on the frame and due to the additional attachment of the clamping member the possibility is created of holding the piece of flat material in the area bordered by the frame in a clamped manner.
In the embodiments described thus far no details have been given as to how superfluous flat material which projects beyond the frame is removed after the piece of flat material has been fixed on the frame. One possibility consists in removing this flat material by cutting.
Another possibility would be to produce blanks for the piece of flat material which already fit prior to it being fixed on the frame so that flat material does not project beyond the frame.
Another advantageous solution provides for the flat material projecting beyond the frame to be cut off by means of a cutting edge when the sonotrode acts on the frame part element.
This solution thus provides for not only a connecting area to be generated due to the action of the sonotrode by way of the melting of the plastic material but also, at the same time, a cutting off of superfluous flat material is possible due to interaction of the ultrasound with the cutting edge provided.
In this case, the cutting edge is preferably provided on a frame part element and, in addition, the cutting edge is preferably designed as a circular, continuous cutting edge so that a separation of the superfluous flat material is brought about, for example, along the entire outer contour of the frame.
The flat material is preferably designed such that it allows a person seated in the motor vehicle to see through it.
Particularly in the case of a wind blocker, the flat material is designed such that it allows the driver to see to the back through the flat material via the rearview mirror.
Furthermore, it is preferably provided in the case of a wind blocker for the flat material to be partially permeable to air, i.e. that the flat material does not represent a compact surface essentially impermeable to air.
This requirement makes it necessary to produce the flat material either as a film with perforations or as a braided, woven or knitted fabric which is permeable to air on account of the intermediate spaces and also allows it to be looked through. Furthermore, the fibers or wires of the piece of flat material are preferably woven so finely that they do not appreciably impede the view through it.
With respect to the material for a braided, woven or knitted fabric, the most varied of solutions are conceivable. In the simplest case, it is provided for these to be fibers, preferably plastic fibers.
It is, however, also conceivable to produce the braided, woven or knitted fabric from inherently inflexible fibers or also as, for example, carbon fibers or wires, in particular, metal wires.